This undated photo provided by the Tuscarawas County Sheriff’s Office shows Robert Clark. Clark, a suspect in the abduction and killing of of Doyle Chumney, 88, and his wife, Lillian, 79, in northeast Ohio Jan. 21, 2015, is now suspected ... more >

CLEVELAND (AP) - A federal warrant was issued Tuesday for a man suspected of abducting and killing an elderly Ohio couple and believed to have committed armed robberies in three states over the weekend.

The FBI said a $20,000 reward was being offered for information about 29-year-old Robert Clark, who is wanted on a charge of unlawful flight to avoid prosecution.

Agents also are looking for Jeffrey Caley Jr., 28, and Tabatha Hazel, 26, who are suspected of participating in the robberies.

Clark has been charged with one count of murder in last month’s killings of 88-year-old Doyle Chumney and his 79-year-old wife, Lillian, of Strasburg, a village 20 miles south of Canton. The couple’s remains were found inside their torched car Jan. 22, a day after they were reported missing.

A second suspect in the slayings, 21-year-old Jeffery Stewart, was arrested Saturday. He also is charged with one count of murder and is being held on $2 million bond. Authorities have said Stewart implicated himself and Clark in the killings.

Clark, Caley and Hazel are suspected of being involved in the armed robberies of gas stations and convenience stores in West Virginia, South Carolina and Georgia on Saturday and Sunday. No one was hurt in the robberies.

A Coshocton County sheriff’s detective said Tuesday that authorities believe the three might be headed to Jacksonville, Florida.

“Someone who knows Tabatha said she had plans to go to Jacksonville,” Detective Tom Couts said.

The trio was last seen during a robbery in Donalsonville, Georgia, on Sunday night, Couts said. Surveillance video shows Clark holding a sawed-off shotgun and Caley holding a pistol as a clerk walks in front of them, the detective said. Hazel went inside the store before Clark and Caley entered, Couts said.

Caley and Hazel were not involved in the Chumney slayings, Couts said. It appears that Clark and Stewart knew each other through a landscaping service where they had worked, Couts said. Clark was released from prison in May after serving a 4 1/2 -year sentence for robbery and other charges.

Couts said authorities believe the Chumneys were driven to a country road in Coshocton County where they were shot before their car was set on fire.

Authorities received a break in the investigation after surveillance video was released publicly showing Clark’s van at a gas station where Stewart bought a gas can and filled it, Couts said. Stewart called police after seeing the video. He was arrested on a traffic warrant and provided statements implicating himself and Clark, Couts said.